Result - End up with screen filled by zoomed into globe (which is somewhat cropped), menu is offscreen. Cursor is trapped in only upper 70% or so of screen.

Alt-Tab back to windows, Alt-Tab back to game

Result - Game is now properly displayed at 3840x2160 but cursor is constrained to sub-region of screen - can get to top right, but can only get as far as the bottom of the text "Anti Aliasing" and about the length of the word "Anti" to the left of the start of that line, so cannot interact with the menu anymore (thus cannot escape the menu, have to alt-tab and kill process to get out).